Amid an AIDS epidemic, against the drumbeat of regional conflicts, overshadowed by the most abject poverty, it is easy to miss the glimmer of hope in sub-Saharan Africa. Rising prices of raw materials are helping the region achieve its best economic performance since independence.

This vitality has fragile foundations. Africa's past commodity booms turned to busts, which means Africans must carefully manage their resources. Western donors must not use the good news as an excuse to shirk their commitments.

In 2005, the Group of 8 leading industrialized nations pledged to increase aid to Africa by at least $25 billion by 2010. Since then, according to the International Monetary Fund, official grants to sub-Saharan Africa have actually declined as a share of its economy.

That is shameful.

If Africa's growth is to be self-sustaining, the wealthy countries must also end their most harmful subsidies on products like cotton and sugar, and aggressively expand market access for the products that African countries can export competitively, like textiles and shoes.

Not only do the offers on the table in global trade negotiations fall short of what is needed, the talks seem at risk of collapsing over disagreements between rich nations and the bigger developing countries.

For the fifth year in a row, growth in sub-Saharan Africa is expected to exceed 5 percent in 2007. That's because of the surging price of oil - a boon for Nigeria and Angola - and rising demand for metals like copper and aluminum that benefit non-oil exporters. Africa has gained substantially from debt reduction. That has freed resources for public investment and underpinned a surge of private foreign investment.

Resource-hungry China has become the region's second-largest trading partner after the United States - and an important investor. There is a dark side to China's role - providing financing and political support to despots like Zimbabwe's Robert Mugabe or Sudan's Omar Hassan al-Bashir - but it is becoming an important engine for the region's economy.

Africa is still dirt poor - with an average annual income per capita of merely $600 and 300 million people living in poverty. Every year, nearly a million children die of malaria and more than 2 million die before they are a month old.

The region is also still locked in the vulnerable role as a supplier of basic commodities. That means its growth will falter if, say, China's economy cools and its demand for raw materials wanes.

Over the long term, Africa must move its way up the chain of commodity exports and into the worldwide networks of manufacturing that account for a growing share of global trade.

The immediate challenge requires investment to deal with historic bottlenecks: dismal health, poor education and derelict infrastructure, notably in transportation and power generation. And it must invest in bringing new technology to agriculture, an essential step to combat entrenched poverty in rural areas. Western aid will be crucial for making progress in all these areas.

Nobody can know for certain whether Africa south of the Sahara might be on the cusp of shaking its endemic destitution and starting up the ladder of development. But it has its best chance in decades, and it would be a crime not to try to grasp this opportunity.